<template>
  <div>
    <router-link 
      tag="div" 
      to="/" 
      class="header-abs" 
      v-show="showAbs">
      <span class="iconfont header-abs-back">&#xe624;</span>
    </router-link>
    <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
      <router-link to="/" >
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
export default {
  name:'DetailHeader',
  data () {
    return {
      showAbs:true,
      opacityStyle:{
        opacity:0
      }
    }
  },
  methods:{
    handleScroll () {
      const top = document.documentElement.scrollTop
      if (top>60) {
        let opacity = top / 140
        opacity = opacity >1 ? 1:opacity
        this.opacityStyle = {
          opacity
        }
        this.showAbs = false
      }else{
        this.showAbs = true
      }
    }
  },
  activated () {
    window.addEventListener('scroll',this.handleScroll)
  },
  deactivated () {
    window.removeEventListener('scroll',this.handleScroll)
  }
}
</script>

<style lang="stylus" scoped>
  @import '~styles/varibles.styl'
  .header-abs
    position :absolute
    left: .2rem
    top: .2rem
    width :.8rem
    height :.8rem
    text-align :center
    line-height :.8rem
    border-radius :.4rem
    background: rgba(0, 0, 0, .8)
    .header-abs-back
      color :#fff
      font-size :.4rem
  .header-fixed
    z-index :2
    position :fixed
    top:0
    left :0
    right :0
    height :$headerHeight
    line-height :$headerHeight
    text-align :center
    color :#fff
    background :$bgColor
    font-size .32rem
    .header-fixed-back
      position :absolute
      top:0
      left :0
      width :.64rem
      text-align :center
      font-size :.4rem
      color:#fff
</style>
